[Seaside] A more complete solution for loose coupling

[Ramon Leon]

>     The kind of stuff that I found quite common and requires 
> a bigger scope than announcements is a case like: when you 
> want update one component lets say aBudgetTotal which is a 
> subcomponent of aBudgetEditor. You want the update only when 
> anItemEditor (also subcomponent of aBudgetEditor) triggers 
> #changed (*key here*) at the user agent. 
>  
>     How would be your (for all of us) favorite approach to this?
>  
> Cheers !
>  
> Sebastian Sastre

ItemEditor has client side event happen that triggers an Ajax updater, the
update triggers an announcement that carries the render canvas as an
argument.  The BudgetEditor is registered to receive this announcement, and
when it happens, uses the renderer contained within to re-render the part of
the page necessary for it.  

I'm just thinking out loud here, I've not tried this, but I see no reason it
wouldn't work, while maintaining total loose coupling between the
components.

Ramon Leon
http://onsmalltalk.com